BMD improvements after operation for primary hyperparathyroidism

Abstract

This study aims to quantify bone mineral density (BMD) changes following surgery in patients with primary hyperparathyroidism (PHPT) and to assess their relationship with clinical and biochemical variables. A historic cohort of 236 PHPT patients with DXA scans pre- and 1-year postoperatively, clinical data, and biochemical data was analyzed. The mean age was 60 years (range 19-86) and 81 % of the patients were women. A significant postoperative 2.6 % (95 % CI, 2.1; 3.1) increase in lumbar spine BMD was seen. The increase in BMD was positively associated with preoperative plasma PTH (p = 0.002), Ca(2+) (p < 0.001), and alkaline phosphatase (p = 0.014). Hip BMD increased 1.5 % (1.1; 1.9). The increase in BMD was positively associated with preoperative plasma PTH (p = 0.005) and Ca(2+) (p < 0.001) and inversely associated with plasma creatinine (p = 0.004) and age (p = 0.018). Total forearm BMD did not change significantly (-0.2 % (-0.5; 0.1)). An increase in forearm BMD was seen in 38 % of all patients, and the changes were positively associated with plasma PTH (p < 0.001) and Ca(2+) (p = 0.009). In all 91 patients with mild PHPT (plasma Ca(2+) < 1.45 mmol/l), there was a significant postoperative increase in spine BMD (1.9 % (1.2; 2.7)) and in hip BMD (1.0 % (0.4; 1.6)), but not in the forearm BMD (-0.3 % (-0.7; 0.2)). The postoperative BMD gain was higher in the hip and forearm in patients operated for adenomas compared with patients treated for hyperplasia. We found significant postoperative BMD improvements both at the hip and the spine. BMD improvements were also significant in mild cases. At all scan sites, there were positive associations between preoperative plasma PTH levels and postoperative BMD increases. The measured BMD changes may mainly be due to a decrease in PTH-induced bone turnover with refilling of the remodeling space.